Classifications

• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
  • H01J61/00—Gas-discharge or vapour-discharge lamps
  • H01J61/02—Details
  • H01J61/30—Vessels; Containers
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
  • H01J61/00—Gas-discharge or vapour-discharge lamps
  • H01J61/82—Lamps with high-pressure unconstricted discharge having a cold pressure > 400 Torr
  • H01J61/827—Metal halide arc lamps
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B60—VEHICLES IN GENERAL
  • B60Q—ARRANGEMENT OF SIGNALLING OR LIGHTING DEVICES, THE MOUNTING OR SUPPORTING THEREOF OR CIRCUITS THEREFOR, FOR VEHICLES IN GENERAL
  • B60Q1/00—Arrangement of optical signalling or lighting devices, the mounting or supporting thereof or circuits therefor
  • B60Q1/02—Arrangement of optical signalling or lighting devices, the mounting or supporting thereof or circuits therefor the devices being primarily intended to illuminate the way ahead or to illuminate other areas of way or environments
  • B60Q1/04—Arrangement of optical signalling or lighting devices, the mounting or supporting thereof or circuits therefor the devices being primarily intended to illuminate the way ahead or to illuminate other areas of way or environments the devices being headlights
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
  • H01J61/00—Gas-discharge or vapour-discharge lamps
  • H01J61/02—Details
  • H01J61/04—Electrodes; Screens; Shields
  • H01J61/06—Main electrodes
  • H01J61/073—Main electrodes for high-pressure discharge lamps
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
  • H01J61/00—Gas-discharge or vapour-discharge lamps
  • H01J61/02—Details
  • H01J61/12—Selection of substances for gas fillings; Specified operating pressure or temperature
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
  • H01J61/00—Gas-discharge or vapour-discharge lamps
  • H01J61/84—Lamps with discharge constricted by high pressure
  • H01J61/86—Lamps with discharge constricted by high pressure with discharge additionally constricted by close spacing of electrodes, e.g. for optical projection

Definitions

• the invention relates to a high-pressure gas discharge lamp comprising at least a lamp tube and two electrodes, wherein the two electrodes are each attached to the lamp tube by a sealed area and, outside the sealed area, each electrode has a perpendicular minimum distance, with respect to its longitudinal axis, from the lamp tube.
• a high-pressure gas discharge lamp comprising at least a lamp tube and two electrodes, wherein the two electrodes are each attached to the lamp tube by a sealed area and, outside the sealed area, each electrode has a perpendicular minimum distance, with respect to its longitudinal axis, from the lamp tube.
• xenon HID (high intensity discharge) lamps are preferably used inter alia in automotive technology, in particular in front headlamps.
• xenon HID lamp also includes similar lamps made by other manufacturers.
• High-pressure gas discharge lamps usually have two electrodes which both fulfill the anode and cathode function in AC operation. These electrodes are often arranged opposite one another in a discharge chamber which is located in the lamp tube. The electrodes in each case have a tip at one of their ends and the electrode base at their other end. The electrode base is connected to the lamp tube, which is usually made of quartz or hard glass. During operation of the lamp, the highest temperature of the lamp tube is usually found in the area where the electrode base enters the lamp tube.
• the distance of the tip of the electrode from the area where the electrode base enters the lamp tube, where the electrode is completely surrounded for the first time, is known as the free path length of the electrode.
• the so-called groove where the material of the lamp tube completely surrounds the electrode base for the first time, is also usually located in this region. A notching in the geometric sense can usually be found at the location of the groove; however, this notching at the location of the groove cannot be found in every case.
• the distance between the location of the groove of the first electrode and the location of the groove of the second electrode is known as the groove spacing.
• the discharge chamber of the high-pressure gas discharge lamp is hermetically sealed and filled in particular with an inert gas.
• An arc discharge is produced in the discharge chamber between the opposed tips of the electrodes, wherein the arc serves as a light source of the high-pressure gas discharge lamp.
• Energy is introduced through the internal electrodes, which are preferably made of tungsten.
• the electrodes are usually connected to an external ballast via molybdenum.
• the molybdenum is usually formed as a molybdenum film or tape and a molybdenum wire.
• the gas-tight closure is usually produced by at least one gas-tight sealed area between the glass-like material, usually quartz, and molybdenum.
• the sealed area may be designed in a known manner as a so-called pinched seal or molybdenum film seal. Since the thermal expansion coefficients of quartz glass and molybdenum are very different, shrinkage of the molybdenum in the sealed area is unavoidable in the event of considerable temperature fluctuations. The gas-tight closure of the sealed area is ensured by the dimensioning of the molybdenum, in particular of the molybdenum film, and of the sealed area.
• the service life of the lamp is furthermore influenced inter alia by the fact that, during operation of the lamp, increased undesirable crystallization of the material of the lamp tube takes place in the region of the electrode base or the sealed area.
• heat is transferred into the region of the sealed area of the lamp tube which serves to attach the electrode to the lamp.
• Undesirable recrystallization of the quartz material of this region, particularly in the sealed area cannot be ruled out but must be kept as low as possible.
• the optical electrode spacing has been standardized in accordance with regulations and should be approx. 4.2 mm.
• optical electrode spacing need not correspond to the actual electrode spacing determined for example by X-ray, that is to say the X-rayed electrode spacing (EAR).
• the optical electrode spacing may vary on account of the different lens effect of the lamp tube or in particular the internal shape thereof; for example there are considerable differences between cylindrical and elliptical internal shapes.
• EP 05700681 Bl discloses a high-pressure gas discharge lamp comprising at least a lamp tube and two electrodes, wherein the two electrodes are attached to the lamp tube by a sealed area and, outside the sealed area, each electrode has a perpendicular minimum distance, with respect to its longitudinal axis, from the lamp tube.
• This type of lamp is commercially available, for example from Philips in the type D2.
• Such a mercury-free lamp is preferably used in automotive technology, in particular in front headlamps.
• the optical electrode spacing is 4.2 mm; the X-rayed electrode spacing (EAR) is approx. 3.7 mm.
• the electrodes consist mainly of a tungsten material, are in each case approximately 6.0 mm long, and the free path length of each electrode is 1.8 mm.
• the groove spacing (RA) is 7.4 mm.
• the transfer of heat from at least one of the electrodes into the respective sealed area can be determined by the dimensioning of the free path length of this electrode and the perpendicular distance between this electrode and the lamp tube outside the sealed area.
• the free path length of the electrode is the length from the electrode tip to the sealed area, that is to say half the difference of groove spacing (RA) and electrode spacing.
• RA groove spacing
• the abovementioned parameters, such as the electrode spacing are actual values which can be determined for example by X-ray, and is therefore for example the X-rayed electrode spacing (EAR).
• the solution according to the invention means that the operating temperature of the lamp can be significantly reduced in the sealed area of the high-pressure gas discharge lamp.
• the electrode head and also the tip thereof are made of the conventional electrode materials, are designed in particular to be solid, and may be differently shaped, for example in the shape of a cylinder, a cone or even a sphere.
• the parts of the electrode, such as the electrode head and the electrode base, are permanently connected to one another by methods known per se or in a known manner.
• the dimensioning of the free path length of this electrode can be influenced by the length of the groove spacing.
• the region of the electrode base has design features, such as a reduced cross section for example, such that the heat conduction there is lower than in the electrode head. This is particularly relevant in electrodes with a relatively large cross section of the electrode head.
• design measures which bring about improved cooling, in particular on account of improved conditions for heat transfer, such as for example the arrangement of cooling ribs, and these may independently thereof be advantageous within the context of the invention.
• design measures this also relates to the choice of materials with regard to the physical properties thereof, such as the density.
• the dimensioning of groove spacing (RA) and maximum perpendicular internal diameter (ID) is selected such that the product of RA and ID is at least 18.5 mm 2 , wherein the maximum perpendicular internal diameter (ID) is less than 2.7 mm. It is furthermore preferred that the product of RA and ID lies in the range from 19.0 to 19.9 mm 2 , at most 25.0 mm 2 .
• the dimensioning of groove spacing (RA), maximum perpendicular internal diameter (ID) and the X-rayed electrode spacing (EAR) is selected in such a way that the product of ID and the difference of RA and EAR is at least 9.5 mm 2 , wherein the maximum perpendicular internal diameter (ID) is less than 2.7 mm.
• the product of ID and the difference of RA and EAR lies in the range from 10.3 to 11.5 mm 2 , at most 15.0 mm 2 . It is moreover preferred that the lamp filling is Hg-free, wherein lamps in the context of the invention may also be high- pressure gas discharge lamps with a mercury filling.
• the lamp and lamp constituents are free of thorium.
• a front headlamp comprising at least one high-pressure gas discharge lamp in accordance with the features of claims 1 to 9.
• Fig. 1 shows a schematic sectional diagram of a lamp tube of a xenon HID high-pressure gas discharge lamp with an electrode arrangement.
• Fig. 1 schematically shows in a sectional diagram a lamp tube 1 with a discharge chamber 2 of a xenon HID high-pressure gas discharge lamp for a front headlamp of a car.
• the lamp tube 1 which is made in one piece and hermetically seals a discharge chamber 2 filled with a gas conventionally used for this purpose, the material of said lamp tube usually being quartz glass, comprises two cylindrical regions of the sealed areas 31, 32 which lie opposite one another and between which there is a region 33 with a maximum perpendicular diameter (ID) of approximately 2.4 mm, that is to say measured perpendicular to the longitudinal axis of the lamp, which in this case is also the longest axis of symmetry of the lamp.
• ID maximum perpendicular diameter
• the electrode arrangement essentially comprises a first electrode 41 and a second electrode 42, between the opposed tips of which an arc discharge is produced in the discharge chamber 2, wherein the arc serves as a light source of the high-pressure gas discharge lamp.
• the optical electrode spacing is 4.2 mm; the X-rayed electrode spacing (EAR) is approximately 3.6 mm in the case of a cylindrical inner contour of the region 33 (not shown in Fig. 1).
• the ends of the electrodes 41, 42 that is to say the electrode bases 43, 44, are connected to the molybdenum wires 61, 62 via the molybdenum tapes 51, 52.
• the molybdenum wires 61, 62 are furthermore connected to the electrical terminals of the lamp (not shown in Fig. 1), via which the supply voltage required to operate the lamp is fed by a power supply, possibly with a ballast, designed for a general mains voltage.
• the electrodes 41, 42 mainly consist of a tungsten material, are shaped in a cylindrical manner and are each approximately 6 mm long; the free path length of the electrodes 41, 42 is 2.2 mm and the electrode base 43 and 44 in each case has a diameter of approximately 0.3 mm.
• the groove spacing (RA) is 8.0 mm.

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• Engineering & Computer Science (AREA)
• Mechanical Engineering (AREA)
• Discharge Lamp (AREA)
• Vessels And Coating Films For Discharge Lamps (AREA)
• Discharge Lamps And Accessories Thereof (AREA)

Priority Applications (4)

Applications Claiming Priority (2)

Publications (2)

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• 2005
  • 2005-10-06 US US11/577,436 patent/US7982377B2/en active Active
  • 2005-10-06 JP JP2007537424A patent/JP4431174B2/ja not_active Expired - Fee Related
  • 2005-10-06 CN CN200580036113A patent/CN100576424C/zh active Active
  • 2005-10-06 WO PCT/IB2005/053283 patent/WO2006043184A2/en active Application Filing
  • 2005-10-06 EP EP05787730.0A patent/EP1805784B1/de active Active
  • 2005-10-06 KR KR1020077011343A patent/KR101160595B1/ko active IP Right Grant

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